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Title: Magnetic properties of heterometallic ruthenium-based clusters
Author: Magee, Samantha
ISNI:       0000 0004 5364 8599
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2014
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This thesis describes the synthesis of ruthenium based molecular clusters and their characterisation. Chapter 2 introduces the concept that the very large zero-field splitting (D = 2.9 cm–1) in the S = 5/2 ground state of [Ru2Mn(μ3-O)(tBuCO2)6(py)3] can be modelled by antisymmetric exchange effects. This is supported by measurement of the single ion D values from the Fe2Mn analogue. The same model is applied to the Ru2Ni analogue to describe the zero-field splitting in the S = 1 ground state, (DGS = +8.0 cm–1 from DNi = -4.0 cm–1) in Chapter 3.Chapters 3 and 4 give the full characterisation of each of the two families, [MIII2MII(μ3-O)(tBuCO2)6(py)3] (MIII = Ru or Fe, MII = Mn, Co, Ni or Zn), through IR, electronic absorption and NMR spectroscopy and are structurally characterised by X-ray diffraction. The total spin ground states and zero-field splitting of those ground states have been ascertained by SQUID magnetometry and EPR spectroscopy. Due to the redox activity of the Ru2M complexes chemical oxidations led to the isolation of [RuIII2CoIIIO(tBuCO2)6(py)3]+ (5) and [RuIIIRuIVNiIIO(tBuCO2)6(py)3]+ (6); the locus of their oxidation was determined with the aid of X-ray absorption spectroscopy (XAS).Chapter 5 shows that due to the ease of the substitution of the terminal ligand in Ru2M they can be linked to other molecular clusters with N-donor ligands, in this case [Cr7NiF8(tBuCO2)15(O2CC5H4N)][NH2Pr2] in order to synthesise [Ru2NiO(tBuCO2)6(py)(Cr7NiF8(tBuCO2)15(O2CC5H4N))2][NH2Pr2]2. In situ oxidation experiments have also been carried out to assess the switchabilty of the redox active linker. Chapter 6 demonstrates a new structural archetype for tetranuclear ruthenium mixed-metal complexes, with the formula, [Ru2M2(µ3-OH)2(tBuCO2)7(py)4], where M is either Co (1) or Ni (2). SQUID magnetometry and EPR spectroscopy have determined the spin ground states as, Seff = 1/2 in 1 and S = 3/2 in 2. The magnetic anisotropy in 2 has been determined as +2.02 cm–1 for the S = 3/2 ground state.
Supervisor: Mcinnes, Eric Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Ruthenium ; Magnetism ; EPR ; carboxylate ; triangle ; zero-field splitting ; anisotropy